#include <fstream>
using namespace std;
int main(){
    ifstream fin("tije.in");
    ofstream fout("tije.out");
      int i,j,k,n; 
    fin>>n;
     for(i=n-1; i>=1; --i){      
         for(j=n; j>=1; --j)
               for(k=1; k<=i; ++k) fout<<j<<" "<<j+1<<"\n";
               }
return 0;
}